Gas purification process and apparatus



June 30, 1931. l A. A. KoHR GAS PURIFICATION PROCESS AND APPARATUS4 2Sheets-Shed 1 File-d July- 15, 1925- INVENTOR .All

June 30, 1931. A. A. KoHR GAS PURIFIGATION PRocEss Ann APPARATUS FiledJuly 13 i925 2 Shadi-Sheet 2 |NVE ma v "ATroRNEYg Patented June 30,A1931.y -k Y ALLIsoN Lioran, orvivrnrnnwoon, Nnw'faiinsnxr; AssrGNonTorHE 'Korrnxs 'coM- v remmer, PITTSBURGH, -rnnitsrmrnnra a con-Ponenciaor PENNSYLVANIA eas runjrrcn'rrcatenciones,AND nrranagjus 1 Applicationniet. Jury. is,

i Thisinvention relates to the purification Y vof fuel gases, such ascoal gas, water gas, and the like, from hydrogen sulphide and analogousimpurities contained by such gases.

VThev 'invention has an .importantv applicaf tion to the practice of gaspurificationy processes described andclainied in the priorcopending'applications of GilbertE. Seil, Ser-" yialNo. 21,978, filedApril`9, 1925,*F1ederick ie W; Sperr, Seria l"Nos.`21,983 and 21,982,both filed April9, 1925, and 'David Ll'jJacobson, Serial No. 520,786,7filed December '8, 1921. Broadly stated, such processes comprise thepurification of fuel, gases from hydrogen i5 sulphide by subjectingtheisaid gases to con` tact with an alkaline `liquid absorbing mediumwherein is suspendedv a inelydivided com'- i poundy of iron..Afsoluti'ony suspension 'that lhas vgivenexcellent results'inpracticecono',- 2-3 prises-a one percent suspension'of ferrie oxide Y ina threeper cent solution of sodiuinfcarv bonate. The solution-suspensionabsorbs the hydrogen'sulphide from the gason :contact with thesame, andis .latersubj ected-to aera-- i 2:5 tion out of contact with the gas,wherebyfthe sulphides present areoxidized to theoriginal Y or otheractive/compounds, with av separation of free sulphur." The s ulphurisremoved fromthe liquid, andv the yrevivified solution-v SO suspensionis' returned to thejcontact appa#l ratus, wherefit is. used once moreyto remove the impurities from Vunpurilied gas. TheL processthuscomprises a cycle of OperationL that includes an absorption phase and:an 51 actification phase. Y L The reactions which effect tlierelnoval ofY Y the hydrogen sulphide and theformation'of y a more anequivalentyamountoffsulphur will Y free sulphur are essentially as follows: e

In the absorber `the hydrogen-sulphide "3") reacts lwiththesodiunicarbonate forming sodium hydrosulphide f e The sodiumhydrosuiphide,reaaslwith fer# ric oxide andsodiurn bicarbonate; f (2)eNaHs+Fe2O3+3NaHCO3=- ;V

The reaction which occursin theactication phaseis essentially: i I A 5'3(f3) '2Fe2S3+3O2v=2jFe2Ol-6S -f AItrk has been' common practice to pumpthe thionizer) that is equipped with yporous aerators of clothorfceramic material, in tubular `'or flat configuration, wherebyair in'finely' e comminuted form is lforced into the solutionsuspension, with'the "resultant accomplishment of reaction VIt will be seen thatalthough there are three Adistinctstep's inthe chemical aspect of thecycle, the' mechanical operation has been conductedin two, and thereaction (2) hasbeen given such little considerationin this; two-phasecycle that 'it is incomplete when aeration commences as the liquidreaches the thionizer. Unless the 'Sulf Phill iS totally, Or practicallysain thezferm of 'aniron" sulphide 4such' as Fe2S3 whenftheliquid'entersthe thionizer, aeration willV notl 'Y be as effective as itshould be by reason of the factthat some of theairthat 'is intended toreact with Lthe ferrie sulphide, is unable .to do l so because thelatterhas notyet beenformedi` f The y consequences of; the incompletereaction t (2),y are heightened yin effect by the costoff forcing airthrough adifusing medium :suchVv Y as the cloth mentioned. Moreover,`underv Y yconditions when `reaction 1 (2) 1s"v incomplete as theVsolution-suspension enters the "thio-y n1ze`r, this-solution-suspenslon' Vwill con# tain undecomposed .sodiumlhydrosulphide (-,Na'HS and under the influence ofaerationthefollowingreactionwilloccur:

I Thus, there is a possibility that'some hydrogen sulphide will escapeinto the atm'os-y be lost to the recovery process.

"It kappears moreoverthatf reaction (2) It has also ybeenffouhd 'bythelfa'pplicant that the presenceof theflnore solubleNaHS v Y in thethionizer'causessome sboppages in the l porous diiusers, withresultantfhigh back pressure, and increased cost of aeration. l'

occurs atk a relatively slower'rate than reac-y j tions (1) @and (3).'ry Consequently, I have provided by'lny invention`Ineansforeffecti,ingthe completion of thQrelativelyfslower reaction' (2)i prior to theaeration stage.

CTI

Such means comprise a reaction tank situate in the line of travel of theliquid leaving the absorber, prior to the entry of the liquid into thethionizer er actilier; the function of the said reaction tank beingsubstantially to effect a Condition of reaction-equilibrium in theliquid before it is aerated to effect reaction In order to furtherfacilitate the completion of the desired reaction (2) means for`agitating the liquid is provided within the said chamber. i/lechanicalagitation may be employed but it is usually preferable to agitate bymeans of a relatively small amount of air conducted through a perforatedpipe. This air is not sul'liciently comminuted to cause full oxidationof the Fe2S3, and the amount used is too small to cause formation of anyappreciable amount of hydrogen su-lphide.

l\ The invention further consists in such other new and usefulimprovements, and has for further objects such other operativeadvantages or results, as may be found to obtain in the processes andappa atus hereinafter described or claimed.

In the accompanying drawings, forming a part of this specification andshowing for purposes of exemplifieation certain form and manner in whichthe invention may be embodied and practiced, but without limiting theclaimed invent-ion to such illustrative instances:

Fig. l is an `elevation partly in section of an installation Lofapparatus .for carrying out the processes; and

Fig. 2 is a plan view of the apparatus shown in F ig. l.

The same characters of reference designate the same parts in each of theviews of the drawings.

In its present embodiment, the invention is applied to the purificationof fuel gases, such as coke ovcn gas from which tar and ammonia havebeen removed; for conveni` ence, the present description will beconfined to the 'above mentioned important application ofthe invention.The invention-is, however, readily susceptible of other valuableapplications; consequently, the invention is not confined in its scopeto the specific use and embodiment herein described asV an illustrativeexample.

In carrying out the invention as shown on the drawings, the gas to bepurified enters the absorber tower A through the gas inlet pipe l andflows upward through the tower, passing out through the gas outlet pipe2. During the trave-l of the` gas through the tower A it comes intointimate contact with the preheated absorbent liquid that `has beensprayed into the absorber through the sprays 3, which absorbent liquidis constituted of dissolved alkali, such as sodium carbonate, or otheralkaline substances, and containing in suspension an iron compound, suchas iron oxide, having an allinity for sulphur. The absorber A is filledwith suitable contact moans, such as the combination of distributive andcontact devices described and claimed in the co-pcnding application ofFrederick W. Sperr, Jr., Serial No. 21,980, tiled April 9, 1925. Theabsorbent liquid7 as it passes downward through the absorber, acquiresby intimate contact with the gas all or the greater part of the sulphurcontent of the same, is indicated in reaction l) above. The spent liquidcollects at the bottom of the absorber A and passes through the sealedoutlet line Il into the reaction tank T1 and the flow into and out ofsaid tank is continuous. The said reaction (2) compartment Il isseparated from the thionizer compartment 'I2 by Vthe vertically disposedAbattle 5, and said reaction (2) compartment is provided in its lowerportion with perforated air pipes 6 that are supplied with air from theair line 7. The liquid is agitated by means of the air Vfrom said airpipes G during the time it remains in the reactiontank T1, and thecontinuous liow into and out Vof said tank T1 is such that the abovementioned. reaction (2) is allowed to complete itself before the liquidoverflows the baille 5 into the thionizer T2. The tank 'Il is ofsullicient size to permit the reactions between vthe. dissolvedsubstances and the substances in suspension to come to substantialcompletion, i. e., to substantial reaction-equilibrium, before thesolution-suspension overflows and enters the actilication phase in theaerating or thionizer compartments. l/Vithin the latter, the liquid isforcibly aerated by means of linely comminuted air to etect morethorough and intimate contact with air, which air is introduced by meansof the tubular aerators 8 placed ltherein, and fed by the air line 9, toeffect reaction Sucli aerators S may be of any convenient and suitableform, but a preferred form is the tubular pliable cloth described andclaimed in the co-pending` application of Gilbert E. Seil, Serial No.21,978, tiled April 9, 1925. The sulphur liberated by such aeration isallowed to rise to the surface, where it accumulates as a foam, whichmay be drawn ohq by means of the foam trough T3, and treated forrecovery ot the sulphur or other constituents thereof. A quick actinggate valve l() is provided for the removal of the foam from the foamtrough T3. The revivitied solution-suspension passes out of thethionizer T2 through the outlet pipes ll to the pump P, which forces itthrough a heater Il and the pipe 12 to the sprays 3 that distribute itto the absorber A. The cycle is thus begun once more.

The design of the thionizer may be subject to variations, for instance,it may be composed of a pluralitv of thionizers similar to the presentillustrative example, and operated either in parallel Vor in series; orthe reaction tank Ti may be separated frointhe thionizer, althougheconomic considerations in construction would indicate that it best 'beY placed as shown or the aeration in compartment T1 may beaccoinplishedin some otherform of aeration device; or instead of locat?ing this reaction tank T1 in connection with# .the thionizer shown itmight be located in connection with the absorber. The essential featureof the present vinvention isthe inter- ]ection of a reaction chamberbetw-een the absorption and actiiication means.

As above stated, the liquid inpassing through the rsaid reactioncompartment .is4

allowed to rid itself of NaHS by completion of the reaction hereinabovementioned. By 'the provision of a separate-compartment operatingprimarily for the purposeiof effecting with certainty reaction (2),there is less chance of stoppages in .the aerating system and the periodin which the aerating tubes are kept iny continuous service islengthened,

thereby reducing the cost of operationy and upkeep.

T he invention as hereinabove set forth or? exemplified may be variouslypracticed or embodied within the scope of the claims here inafter made.f

l. In a process of'purifying gases .contain-V ing hydrogen sulphide, thecombination of steps which consists in: Wasliingthe gas with an'alkalinesolution containing aniron conipound'liaving an aiiinity for sulphur;then passing the spent washeliquor through a reaction phase to causetheiron compound toy absorb substantially all of the sulphur Kreinaining inalkaline solution; .then passingAv the spent solution after suchreactionthrough a regenerative phasein which the spentv solu' tion issubjected to f the faction of 'finely Y atomized air to effect thoroughand intimate` contact of air with kthefspent liquor; withl` drawing thefree sulphur .that iioats to the surface, and then heating and returningthe Vregenerated solution to the gas washing phase.

2 In a process of Yliquid Apurification of i gases involving anabsorption phase, in which a preheated sodium carbonate :solutioncontaining iron oxide is brought into intimate and thorough contact withthe gas to be purif fied to absorbl the hydrogen-sulphide therefrom andto form iron sulphide, and involv-v ingl an actiiicationphase invwhichthe spent solution is brought into intimate and thoroughv contact withfinely atomized air 'to regenerate the iron sulphide to form iron oxidevwithliberation offree sulphurwhich floats to the surface, theimprovement which consists in preliminarilyagitating the spenti iliquorwith air, before it reaches the actifica-v tion phase, to causethe sulphurof the remainf ingsodium hydrosulphide to combine with" t theiron of the iron oxide forthe formation of iron sulphide` which, whenaerated with .finely :itemized air in they actiiication phase, fis morereadily converted l tojwironlgoxide, adapted lforffurther y,useinabsorbing-hy#- drogen'sulphide from gases, Aand freesulphur withoutsubstantial formation of hydrogen sulphide,I s Y' 'i action phase, tocause 'the iron compound to absorb, substantially all of thesulphu-r re-'mig m'ainingin alkaline solution; then` passingl the spent solution-after fr such` "reaction i through a regenerativeA phase in Iwhich,ther spent solution `is subjected toftlielactionfof f .finely` atoniizedair'to effect; thorough and intimate contactiofair'with the spentliquor;

witlidrawingthe free--sulpliurithatiioats to*` the surface, and thenlreturning the regen# erated solution to the gas'washingphase.4 I 4. AIna process of. purifyingfgas'es containfing hydrogen sulphide, theycombination` -of steps which .consists in: washingthe gas with analkaline solution containing anfiron compound having an fafflnityvfgo'rsulplnur; then passing the spent; wash-liquor through areactionlphase to causegthe'iron compoundyto miv absorbsubstantiallyallyofitlie 'sulphur rreinaining in alkaline solution ;-thenvrpassingthe spentfsolutionafter Asuch reaction through a lregenerativephase-in whichthefspent'solu#y ,tion is subjectedto the actionofiinelyatoni.- v ized. air to effect thoroughA and intimatefconjioo tact of airwithithe spentliquor ,withdrawing i the free sulphur, and .thenVreturningfthel` f regenerated Vsolution to theV gas washing phase; 1yr.f

5. Ina gaspurication process comprising f `a v'hydrogen-sulphide jabsorption-phase and an actiiicationfphase wherein. anl alkaline sofv'lution containing a ,compound-of-aJ ,metal whose sulphide is insolubleis circulated toababsorption phase andthe spent liquor is resorb thehydrogenssulp'hide impurities inthe generatedin the actiicationphase,the.im

provement comprising causingythe `reactions between ,thealkalinesolutionfand thenietal n p compound fortheformationofmetallicsulf phide torcome to substantial com letionbeforethe spent liquor enters the actiication phase. 6.V Aprocess/as'claimed in'claim 5 charac. terized by agitating the liquidundergoing izo substantial completion ofreactions to faoilil tate thereaction between the alkaline solution l y Vand the metalcoinpound.vr ai n 7. In a process of purifying gases contain! ingghydrogensulphide,the combination of stepsy comprising: Washing the gas .with an alkalinesolution containing a compound of a metal whose sulphide is insoluble;then'pass-A y ing the spent wash-liquorvthrough a reaction' phase tocause said compound of a metal to absorb substantially all of thesulphur remaining in alkaline solution 5 then passing the spent solutionafter ysuch reaction through a regenerative phase in Which the spentsolution is subjected to 'the action of finely comminuted air toregenerate said metallic coinpound with liberation and flotation of freesulphur; withdrawing the free sulphur that floats to the surface; andthen returning` the regenerated solution to the gas Washing phase.

8. In a proces of purifying gases containing lhydrogen sulphide7 thecombination of steps comprising: Washing the gas with an alkaline`solution containing a compound of a metal Whose sulphide is insoluble;then passing the spent Wash-liquor through a reaction phase to causesaid compound of a metal to absorb substantially all of the sulphurremaining in alkaline solution; then passing the spent solution aftersuch reaction through a regeneration phase in which the spent solutionis subjected to the action of finely comminuted air to regenerate saidmetallic compound With liberation of free sulphur; and then returningthe regenerated solution to the gas Washing phase.

9. Apparatus for regeneration of fouled liquid from a gas puriiicationprocess comprising in combination: a reaction chamber; a regenerationchamber; said reaction chamber being adapted to occasion substantialcompletion of absorption reactions in fouled liquid and having liquidaerating means therein adapted for agitating liquid therein so as toeffect an acceleration and completion of absorption reactions in theliquid with minimum regenerating action therein; said regenerationchamber being adapted to occasion regeneration of fouled liquid fromsaid reaction chamber 'and having aerating'means therein adapted forsupplying 'Iinely comminuted gas to liquid therein so as to effect arela-tively greater regenerating` action therein; said reaction chamberand said regeneration chamber being constituted as compartments of thesame tank and being so coinmunicably connected with each other thatliquid entering the reaction chamber traverses said cha-1nber beforepassage into the regeneration chamber.

In testimony whereof I have hereunto set my hand. y I

ALLISON A. vIsrGl-IR.

